[PATCH V4 23/27] selftests: ublk: handle UBLK_U_IO_PREP_IO_CMDS

Ming Lei
2025-11-21T02:00:44Z

Implement support for UBLK_U_IO_PREP_IO_CMDS in the batch I/O framework:

- Add batch command initialization and setup functions
- Implement prep command queueing with proper buffer management
- Add command completion handling for prep and commit commands
- Integrate batch I/O setup into thread initialization
- Update CQE handling to support batch commands

The implementation uses the previously established buffer management
infrastructure to queue UBLK_U_IO_PREP_IO_CMDS commands. Commands are
prepared in the first thread context and use commit buffers for
efficient command batching.

Key changes:
- ublk_batch_queue_prep_io_cmds() prepares I/O command batches
- ublk_batch_compl_cmd() handles batch command completions
- Modified thread setup to use batch operations when enabled
- Enhanced buffer index calculation for batch mode

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
tools/testing/selftests/ublk/batch.c | 113 +++++++++++++++++++++++++++
tools/testing/selftests/ublk/kublk.c | 46 ++++++++---
tools/testing/selftests/ublk/kublk.h | 22 ++++++
3 files changed, 171 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/ublk/batch.c b/tools/testing/selftests/ublk/batch.c
index 609e6073c9c0..01f00c21dfdb 100644
--- a/tools/testing/selftests/ublk/batch.c
+++ b/tools/testing/selftests/ublk/batch.c
@@ -150,3 +150,116 @@ void ublk_batch_free_buf(struct ublk_thread *t)
{
free_batch_commit_buf(t);
}
+
+static void ublk_init_batch_cmd(struct ublk_thread *t, __u16 q_id,
+ struct io_uring_sqe *sqe, unsigned op,
+ unsigned short elem_bytes,
+ unsigned short nr_elem,
+ unsigned short buf_idx)
+{
+ struct ublk_batch_io *cmd;
+ __u64 user_data;
+
+ cmd = (struct ublk_batch_io *)ublk_get_sqe_cmd(sqe);
+
+ ublk_set_sqe_cmd_op(sqe, op);
+
+ sqe->fd = 0; /* dev->fds[0] */
+ sqe->opcode = IORING_OP_URING_CMD;
+ sqe->flags = IOSQE_FIXED_FILE;
+
+ cmd->q_id = q_id;
+ cmd->flags = 0;
+ cmd->reserved = 0;
+ cmd->elem_bytes = elem_bytes;
+ cmd->nr_elem = nr_elem;
+
+ user_data = build_user_data(buf_idx, _IOC_NR(op), 0, q_id, 0);
+ io_uring_sqe_set_data64(sqe, user_data);
+
+ t->cmd_inflight += 1;
+
+ ublk_dbg(UBLK_DBG_IO_CMD, "%s: thread %u qid %d cmd_op %x data %lx "
+ "nr_elem %u elem_bytes %u buf_size %u buf_idx %d "
+ "cmd_inflight %u\n",
+ __func__, t->idx, q_id, op, user_data,
+ cmd->nr_elem, cmd->elem_bytes,
+ nr_elem * elem_bytes, buf_idx, t->cmd_inflight);
+}
+
+static void ublk_setup_commit_sqe(struct ublk_thread *t,
+ struct io_uring_sqe *sqe,
+ unsigned short buf_idx)
+{
+ struct ublk_batch_io *cmd;
+
+ cmd = (struct ublk_batch_io *)ublk_get_sqe_cmd(sqe);
+
+ /* Use plain user buffer instead of fixed buffer */
+ cmd->flags |= t->cmd_flags;
+}
+
+int ublk_batch_queue_prep_io_cmds(struct ublk_thread *t, struct ublk_queue *q)
+{
+ unsigned short nr_elem = q->q_depth;
+ unsigned short buf_idx = ublk_alloc_commit_buf(t);
+ struct io_uring_sqe *sqe;
+ void *buf;
+ int i;
+
+ ublk_assert(buf_idx != UBLKS_T_COMMIT_BUF_INV_IDX);
+
+ ublk_io_alloc_sqes(t, &sqe, 1);
+
+ ublk_assert(nr_elem == q->q_depth);
+ buf = ublk_get_commit_buf(t, buf_idx);
+ for (i = 0; i < nr_elem; i++) {
+ struct ublk_batch_elem *elem = (struct ublk_batch_elem *)(
+ buf + i * t->commit_buf_elem_size);
+ struct ublk_io *io = &q->ios[i];
+
+ elem->tag = i;
+ elem->result = 0;
+
+ if (ublk_queue_use_auto_zc(q))
+ elem->buf_index = ublk_batch_io_buf_idx(t, q, i);
+ else if (!ublk_queue_no_buf(q))
+ elem->buf_addr = (__u64)io->buf_addr;
+ }
+
+ sqe->addr = (__u64)buf;
+ sqe->len = t->commit_buf_elem_size * nr_elem;
+
+ ublk_init_batch_cmd(t, q->q_id, sqe, UBLK_U_IO_PREP_IO_CMDS,
+ t->commit_buf_elem_size, nr_elem, buf_idx);
+ ublk_setup_commit_sqe(t, sqe, buf_idx);
+ return 0;
+}
+
+static void ublk_batch_compl_commit_cmd(struct ublk_thread *t,
+ const struct io_uring_cqe *cqe,
+ unsigned op)
+{
+ unsigned short buf_idx = user_data_to_tag(cqe->user_data);
+
+ if (op == _IOC_NR(UBLK_U_IO_PREP_IO_CMDS))
+ ublk_assert(cqe->res == 0);
+ else if (op == _IOC_NR(UBLK_U_IO_COMMIT_IO_CMDS))
+ ;//assert(cqe->res == t->commit_buf_size);
+ else
+ ublk_assert(0);
+
+ ublk_free_commit_buf(t, buf_idx);
+}
+
+void ublk_batch_compl_cmd(struct ublk_thread *t,
+ const struct io_uring_cqe *cqe)
+{
+ unsigned op = user_data_to_op(cqe->user_data);
+
+ if (op == _IOC_NR(UBLK_U_IO_PREP_IO_CMDS) ||
+ op == _IOC_NR(UBLK_U_IO_COMMIT_IO_CMDS)) {
+ ublk_batch_compl_commit_cmd(t, cqe, op);
+ return;
+ }
+}
diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index 29594612edc9..e981fcf18475 100644
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -795,28 +795,32 @@ static void ublk_handle_cqe(struct ublk_thread *t,
{
struct ublk_dev *dev = t->dev;
unsigned q_id = user_data_to_q_id(cqe->user_data);
- struct ublk_queue *q = &dev->q[q_id];
unsigned cmd_op = user_data_to_op(cqe->user_data);

if (cqe->res < 0 && cqe->res != -ENODEV)
- ublk_err("%s: res %d userdata %llx queue state %x\n", __func__,
- cqe->res, cqe->user_data, q->flags);
+ ublk_err("%s: res %d userdata %llx thread state %x\n", __func__,
+ cqe->res, cqe->user_data, t->state);

- ublk_dbg(UBLK_DBG_IO_CMD, "%s: res %d (qid %d tag %u cmd_op %u target %d/%d) stopping %d\n",
- __func__, cqe->res, q->q_id, user_data_to_tag(cqe->user_data),
- cmd_op, is_target_io(cqe->user_data),
+ ublk_dbg(UBLK_DBG_IO_CMD, "%s: res %d (thread %d qid %d tag %u cmd_op %x "
+ "data %lx target %d/%d) stopping %d\n",
+ __func__, cqe->res, t->idx, q_id,
+ user_data_to_tag(cqe->user_data),
+ cmd_op, cqe->user_data, is_target_io(cqe->user_data),
user_data_to_tgt_data(cqe->user_data),
(t->state & UBLKS_T_STOPPING));

/* Don't retrieve io in case of target io */
if (is_target_io(cqe->user_data)) {
- ublksrv_handle_tgt_cqe(t, q, cqe);
+ ublksrv_handle_tgt_cqe(t, &dev->q[q_id], cqe);
return;
}

t->cmd_inflight--;

- ublk_handle_uring_cmd(t, q, cqe);
+ if (ublk_thread_batch_io(t))
+ ublk_batch_compl_cmd(t, cqe);
+ else
+ ublk_handle_uring_cmd(t, &dev->q[q_id], cqe);
}

static int ublk_reap_events_uring(struct ublk_thread *t)
@@ -873,6 +877,22 @@ static void ublk_thread_set_sched_affinity(const struct ublk_thread_info *info)
info->dev->dev_info.dev_id, info->idx);
}

+static void ublk_batch_setup_queues(struct ublk_thread *t)
+{
+ int i;
+
+ /* setup all queues in the 1st thread */
+ for (i = 0; i < t->dev->dev_info.nr_hw_queues; i++) {
+ struct ublk_queue *q = &t->dev->q[i];
+ int ret;
+
+ ret = ublk_batch_queue_prep_io_cmds(t, q);
+ ublk_assert(ret == 0);
+ ret = ublk_process_io(t);
+ ublk_assert(ret >= 0);
+ }
+}
+
static __attribute__((noinline)) int __ublk_io_handler_fn(struct ublk_thread_info *info)
{
struct ublk_thread t = {
@@ -893,8 +913,14 @@ static __attribute__((noinline)) int __ublk_io_handler_fn(struct ublk_thread_inf
ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %u started\n",
gettid(), dev_id, t.idx);

- /* submit all io commands to ublk driver */
- ublk_submit_fetch_commands(&t);
+ if (!ublk_thread_batch_io(&t)) {
+ /* submit all io commands to ublk driver */
+ ublk_submit_fetch_commands(&t);
+ } else if (!t.idx) {
+ /* prepare all io commands in the 1st thread context */
+ ublk_batch_setup_queues(&t);
+ }
+
do {
if (ublk_process_io(&t) < 0)
break;
diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
index e75c28680783..51fad0f4419b 100644
--- a/tools/testing/selftests/ublk/kublk.h
+++ b/tools/testing/selftests/ublk/kublk.h
@@ -398,10 +398,16 @@ static inline void ublk_set_sqe_cmd_op(struct io_uring_sqe *sqe, __u32 cmd_op)
addr[1] = 0;
}

+static inline unsigned short ublk_batch_io_buf_idx(
+ const struct ublk_thread *t, const struct ublk_queue *q,
+ unsigned tag);
+
static inline unsigned short ublk_io_buf_idx(const struct ublk_thread *t,
const struct ublk_queue *q,
unsigned tag)
{
+ if (ublk_queue_batch_io(q))
+ return ublk_batch_io_buf_idx(t, q, tag);
return q->ios[tag].buf_index;
}

@@ -464,6 +470,22 @@ static inline int ublk_queue_no_buf(const struct ublk_queue *q)
return ublk_queue_use_zc(q) || ublk_queue_use_auto_zc(q);
}

+/*
+ * Each IO's buffer index has to be calculated by this helper for
+ * UBLKS_T_BATCH_IO
+ */
+static inline unsigned short ublk_batch_io_buf_idx(
+ const struct ublk_thread *t, const struct ublk_queue *q,
+ unsigned tag)
+{
+ return tag;
+}
+
+/* Queue UBLK_U_IO_PREP_IO_CMDS for a specific queue with batch elements */
+int ublk_batch_queue_prep_io_cmds(struct ublk_thread *t, struct ublk_queue *q);
+/* Handle completion of batch I/O commands (prep/commit) */
+void ublk_batch_compl_cmd(struct ublk_thread *t,
+ const struct io_uring_cqe *cqe);
/* Initialize batch I/O state and calculate buffer parameters */
void ublk_batch_prepare(struct ublk_thread *t);
/* Allocate and register commit buffers for batch operations */
--
2.47.0